Method and apparatus for drilling boreholes



June 9, 1953 J. MOON 2,641,444

METHOD AND APPARATUS FOR DRILLING BOREHOLES Filed Sept. 3, 1946 2 Sheets-Shet 1 ATTORNEY METHOD AND APPARATUS FOR DRILLING BOREHOLES Filed Sept.s. 1946 J. MOON 2 Sheets-Sheet 2 June 9, 1953 I IINVENTOR.

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I, JWM VYW R 4 Patented June 9, 1953 METHOD AND APPARATUS FOR DRILLINGBOREHOLES ames Moon, Altadena, Calif., assignor to Signal Oil and GasCompany, Los Angeles, Calif., a

corporation of Delaware Application September 3, 1946, Serial No.694,561

This invention relates to a method and apparatus for drilling boreholes, and particularly to the drilling of drill holes to apredetermined gauge and also to the drilling of bore holes to traverse apredetermined course in the earth. In the drilling of bore holes by therotary method so as to traverse av straight vertical path, it has beenpreviously suggested that the drill pipe be advanced together with anaccompanying straight guide casing in which'the drill tubeis supportedfor rotation. I

It has also been suggested that in drilling deviated bore holes thedrill pipe be guided in a casing which has been previously bent to thecurve which the drill tube is to traverse in drill? ing the bore hole.

This invention is an improvement in such methods and in such apparatus.

In such drilling procedure, in common with normal drilling inside ofuncased holes where no guide casing is employed, it has been founddesirable to limit the load on the drill pipe. The static weight of thedrill pipe is frequently too great a load on the drill. The result is abending and severe whipping and even corkscrewing, of the drill pipe.Such bending, whipping, and corkscrewing cause the drilling of a borewhich is not true to gauge and in which large caves are created and alsocause the bore hole to deviate in the wall of the bore. This whippingand corkscrewing also cause such reversals of the stress that a materialshortening of the effective life of the pipe results.

In drilling in cased holes with advancing casing, the load which may beimposed on the drill 6' Claims. (Cl.- 255-1.s

through the jets of the drill at equal mud pump pressure.

Additionally, the abrupt change in tube wall thickness, particularly atthe point where the stress changes from tension in the drill pipe tocompression in the drill collar, is a. point of weakness, and sinceunder modern drilling controls it is impossible for the driller tolocalize and maintain invariant the point where thisstress changes inphase from tension to compression, failure occurs at the juncturebetween the drill tube and is likewise limited, due to the largeslenderness ratio of the column of drill pipe. It bends under load,whips, and corkscrews in the casing, causing similar damage to thecasing and drill pipe and deviation of the bore hole.

It has therefore been the practice in drilling to limit the load on thedrill by'supporting-the, weight of the drill pipe so that the drill pipeabove the drill collar is in tension and only the weight of the drillcollar is imposed on the drill. The use of drill collars forimpartingweight to the drill and to give rigidity to the section of thedrill string above the drill has imposed certain serious limitations.Such drill collars are substantially of the external diameter of thedrill pipe, but in order to have great weight and be more rigid than thedrill pipe, they are of much smaller internal diameter. This'imposes aserious back pressure on the circulating drilling fluid and reduces thevelocity of the drilling fluid the drill collar. This also causevariations in stress throughout the entire drill stem.

Additionally, in drilling with an advancing casing one of thedifficulties is to maintain the relationship between theend of thecasing and the drill such that the drill does not advance too far aheadof the casing to be properly guided thereby. 3 I have developed a methodand apparatus for drilling which overcome these difi'iculties.

In my method of drilling, employing the apparatus of my invention, Iload the drill which is, as conventional, attached to the end of thedrill pipe, not by the drill pipe, but by guide casing, whose advance iscontrolled independently of the advance of the drill string, so that thedrill is advanced by the load of the casing against a restraining ,forceon the drill pipe imposed at or near the other end of the drill pipewhich tends 'tohold the drill pipe back. The load imposed on the drillby the casing is held sufliciently greater than the restraining force bythe independently controlled casing advancing means to advance the drillat the desired rate.

The drill stem from the surface of the ground to the point ofapplication of the casing load is maintained in tension. This casingload is applied immediately above the drill so that drill collars arenot needed, or if needed are not relied upon to load the drill.

For this reason the point of application of weight on the drill remainsconstant and no section of the drill stem is subjected to stresses whichfluctuate in phase.

Since drill collars are largely eliminated, or may be completelyeliminated, the restriction on mud flow which they impose is alsoeliminated.

The phenomenon of destructive forces in drill pipe caused by theseuncontrolled vibrations results in enormous shock loads which in turngreatly shorten the useful life of the drill, and in many cases causes apermanent deformation of corkscrew character in the drill pipe.

' By loading the drill pipe with casing according to my invention, alarge reduction of the bending forces in the pipe results, so that thepositioned in the openings 50a, making a sliding fit therein. The head52 is recessed to receive the bolt '53 which holds the flexible cupwasher '55. The spring 54 is mounted between the end of the chamber 50and Washer 55. The casing an. internal collar-.56 welded thereto. Thecollar terminates in ashouider 51.. The drill is connected to the shaft24 at 58.

With the drill string assembled and in position, as shown in Fig. l, butwith the casing reby the: hydraulic jacks 9 so that the fluid in theannulus betweerf the-easing arid the;

wall. All of these factors aid the casing ill-9315* sorbing these loadswithout. damage.

These objects and advantages will be clear to those skilled in the artby the following description when taken together with thedrawings, in

which Fig. 1 is a view of the drill string according to o my inventionin position in drilling a well;

. F g. .2 is a detail of. the drill and thrust head.

shown n Fig. 1"; Fig, 3 is a vertical section through. the thrust head;

Fig. 4: is a section taken on. line 4-4 of Fig. 2;. and;

Fig- 5 is. a. section taken. on. the. line 5---& of Fig, 3.

In: well; bore l is positioned the conventional conductor pipe carryinga packer seal 3 and a mud inputipipel The. packer may be. of thedesignshown. more. fully in my copending application Serial No.653,875,.filed March 12, 1946,, now abandoned, is herewith. incorporatedby reference.

Aca'sing 5. passes through the packer e and is supported on. a yoke 6carrying supporting slips T, Theyoke is advanced and retractedby pistonrods. 8 of hydraulic. jacks 9.. The drill string composed v of. aconventional kelly to and; drill tubing. H isrotated by a conventionalrotary table t2 and supported by the. swivel. t5, block I24 and line 5passing over the crown. block. (6 ot a derrick. IT and the. line 5'passing over. the conventional. hoist 18;

In place: of; or in. addition. to the conventional drill collars thedrill. tubing. carries adjacent the drill ISl' carries conventional.expansible and retractable reamers 20; the. thrust head if, carrying thepins? 22. The load of. the casing 5 istransmitted to the pins by meansoil the casing collar 23;

- The thrust head. is composed of a hollow shaft 24 which isconnectedvia threads 25 and tool joint 26 to the drilltubing IL. Thisconstruction permits of the tension. loading. oi the drill pipe and isa.secure connection. under such. tension. The collar 23, formed with.lugs 28a, has ashoulden 39' which is mounted on shoulder oil the shaft24 by means of bearingsv 4i. i

The collar 23' is spaced from. the shaft. 2.4 and the space is sealed atthe top by means of packers 3Q retained in packer ring 29.. A hearing33' retained in packer ring 29 by meansoi shoulders 34 and by shoulder32 on'collar Z8. A further seal! is provided by packer 34 retained. byshoulder to and ring 35. Sealing is further provided. bypacker soretained by shoulder 31 and. ring 38. A further bearing. 44 is retainedon ring. 42 by means of. shoulder 43 and end. shoulder 43 of packerring. 45'"- in. which is positioned the packer 41 retained by ring. 48-.

The shaft 24' carries ports 21 which. are in registry thechamber Manorecesses 50m in shoulder 51 is raised above the pins 5|, the mudcirculating through 4, down the tubing 1 l and.

' through. the iets of the drill, exerts a pressure Iii on the washers5a to move the pins 5| outward against the spring 54. The casing is thenlowered the shouldez 51 engages the head 52, as shown. in Fig. 2. Theweight of the casing is thus imposed on the pins 5|. The mud is alsocirculated through line 4 down the annulus. be-

the casing and; bore wall and joinsthe mud descending through the drillpipe it, re

. turning; up between the casing and drill pipe to the collar 28= andlugs 28a. Pins. 54', whose axes are atoll to themes of: thesha 2. a e

discharge through line I la to the-mud pit.

The load imposed; by the casing is regulated by the load impose-d byth'ehydraulic jacks which can. cause. the advance of the casing and may becontrolled independently of the advance of the drill string. more orless of the static weight of the casing is imposed on the pins" by thejacks. If the jacks impose" an upward thrust on the yoke, some oi. thestatic: load is taken up by this upward thrust or if the jacks impose adownward thrust on. the yoke, this additional load is added to theweight of the casing.

Part or all. of the weight of the? drill pipe may be taken up by thetension on line to. The net static load on the drill is thus thedifference icetween the weight of the drill pipe and the tenin pounds.-on the line f5, e-., the load on the hook. In drilling ahead. this loadis less than the static load by the amount of this pull which acts as aretarding fierce; or upward thrust on the casing. It is thus possible.to determine the load conditions on the drill during drilling when thedrill is by the. casing and the drill pipe. In order to minimizefriction; drilling fluid is circulated through input line 4 anddown theannulus between the casing and the bore h'oie and circulated togetherwith the mud passed through the drill pipe; back up inside the casing.This not only reduces the friction between thecasing and the bore holeto a negligi-bi-e degree,

' but also has the addit"I'on'al advantages set forth in the co-pen'dingapplication, Serial No. 653 ,8'75 With the required load imposed by thecasing on the head, the drill pipe and drill are rotated in thebearings". A restraining force is imposed by the line E5 in amount.greater than the static of the: drill. string above the thrust collar;so that: the: drill pipe above the thrust collar is. throughout its;length. entirely tension. The entire compression load. on; the thrustcollar and. drill is the load imposed by the casing. The drill pipe is:thus pulled into the Home against therestraining force of: the. line.This'restraining fierce. is less than the static weight of the casinganddrill pipe,- ignoring friction may lie-negligible in view of thelubricating effectof the mud and the enlargement of the: bore causedv bythe. reamer 201, as shown. in Fig: 1. p This diiierence constitutes. theload on the bit. I Witl i; the driI-Lpipe. entirely tensionthe drillconventional tensiorneter in the line.

pipe is not under any flexure load and rotates with substantially nowhip or winding up.

Unlike conventional drilling operations, the load on the bit is a steadyload. The drill pipe does not jump up and down in the hole as it does inpresent practice. The load on the bit is localized and remainsstationary at the lugs 54 so that no change in load phase from tensionto compression occurs at any joint or plane in the drill assembly.

Since the load on the drill is an external load and not due to anyweight imposed by drill collars or the drill tubing, the restrictionimposed by the restricted bore of the drill collars is avoided and theback pressure on the circulating mud is reduced.

When the drill tubing is supported on a line 15, the load on the linemay be measured by a Instead of supporting the drill tubing on a line,it may be supported and moved by means of hydraulic cylinders asdescribed in my co-pending app-lication identified above.

While I have described this invention as ap plied to drilling of avertical bore, it is also applicable to the drilling of horizontal boresor deviated bores by the drilling procedures described in my co-pendingapplication Serial No. 949,719, filed January 1949, now abandoned, or bythe process and apparatus oi the copending applications of Garth L.Young, Serial No. 629,543, filed November 19, 19.45, now abandoned, andSerial No. 619,749, filed October 2, 1945, now Patent No. 2,565,794issued August 28, 1951.

In the previous discussion, I have described the application of mymethod and apparatus as applied to the preferred embodiment wherein thedrill pipe is entirely in tension and substantially the entirecompressive load is that resulting from the loading of the pins by thecasing. sired for any reason, the drill may also be loaded by the drillpipe by reducing the amount of tension on the line is so that part ofthe static load of the drill pipe is transmitted to the drill.

While I have described a particular embodiment of my invention for thepurpose of illustration, it should be understood that various modifications and adaptations thereof may be made Within the spirit of theinvention as set forth in the appended claims.

I claim:

1. A method of rotary drilling, which comprises rotating and advancing astring of drill pipe to which a drill is attached. at one end thereof inthe earth to form a bore hole, advancing a casing in said bore holeindependently of and simultaneously with the advance of said string ofdrill pipe, transferring the weight of said casing to said drill during,drilling, and advancing and simultaneously restraining the drill pipeagainst said advance by a restraining force imposed near the other endof said drill string, whereby the load of said casing advances saidstring of pipe against said restraining force.

2. A method of rotary drilling, which comprises rotating and advancing astring of drill pipe to which a drill is attached at one end thereof inthe earth to form a bore hole, advancing a casing in said bore hole,independently of and simultaneously with the advance of said string ofdrill pipe, imposing a thrust load on said casing, transferring thethrust of said casing to said drill pipe during drilling, and advancingsaid drill pipe and also simultaneously restraining the drill pipeagainst said advance by a restraining If deforce near-the other end ofsaid drill pipe, whereby the thrust of said casing advances said drillpipe against said restraining force.

3. A drilling device, a comprising a thrust collar, a central bore insaid collar, a hollow shaft rotatably mounted in said central bore ofsaid thrust collar, means for connecting one end of said shaft to astring of drill pipe, means for con necting the other end of said shaftto a rotary bore hole drill, a plurality of extensible pins in saidcollar, the axes of said pins being positioned at about to the axis ofsaid shaft.

4. A rotary drilling device, comprising a thrust collar, a hollow shaftcoaxial with said thrust collar, bearings between said shaft and saidcollar, packing between said shaft and said collar, means for attachingsaid shaft to the drill pipe of a rotary earth drilling device, meansfor attaching the other end of said shaft to the drill of said rotarydrilling device, a port in said shaft, a bore in said collar in fluidcommunication with said port in said shaft, 2. pin slidably positionedin said bore, and a spring mounted in said bore, hydraulic means formoving said pin against said spring upon the imposition of fluidpressure in said shaft to move said pin in said bore to extend said pinexteriorly of said collar.

5. In a rotary earth bore hole drilling device for Wells, a string ofdrill pipe, means at the surface of the ground for rotating andadvancing said string, a drill attached to the end of said drill pipe, athrust collar coaxially mounted on said drill pipe adjacent said drill,bearings between said thrust collar and said drill pipe, pins movablypositioned in bores in said thrust collar, means for extension of saidpins outwardly,

from said collar, a casing concentrically mounted with said drill pipe,and means at the surface for suspending and advancing said casing, saidcasing resting upon said pins when said pins are extended externally ofsaid thrust collar.

6. In a rotary earth bore hole drilling assembly in combination, drillpipe, means at the surface of the ground for rotating and advancing saiddrill pipe, a drill mounted at the end of said drill pipe, a thrustcollar concentrically mounted upon said drill pipe adjacent said drill,bearings between said thrust collar and said drill pipe, a bore in thewall of said drill pipe, a plurality of bores in said thrust collar influid communication with the bore in said drill pipe, pins resilientlymounted for movement in the bore of said thrust collar, a casingconcentric with said drill collar, means at the surface for supportingand advancing said casing, a collar mounted upon said casing adapted torest upon said pins of said thrust collar when said pins are extended insaid bore of said thrust collar, means for extending said pins in saidbore of said thrust collar upon the imposition of fluid pressure in saiddrill pipe.

JAMES MOON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 804,092 Brants Nov. '7, 1905 1,147,898 Seitz July 27, 19151,166,011 Shaffer Dec. 28, 1915 1,391,626 Gilthorpe Sept. 20, 19211,894,039 Hill Jan. 10, 1933 2,100,419 Wright Nov. 30, 1937 2,112,254Stokes Mar. 29, 1938 2,242,279 Young May 20, 1941 2,292,126 Isley Aug.4,1942

